This research aimed to understand Japan's foreign policy in the 1970s in a comprehensive way, by analyzing how Japan reacted to international changes of the days. Normalization of the U.S.-China diplomatic relations, the end of Bretton-Woods system, Detente, increasing inter-dependence between Japan and Asian countries, all of which occurred in the 1970s, compelled Japan to broaden its foreign policy interfaces, that is depolying more "autonomous" diplomacy and multi-lateral foreign relations. We tried to make sense of this adjustment process.In order to conduct this research, we need to interview politicians, diplomats, and other bureaucrats who playd significant roles in this adjustment processes, because of "newness" of these events, though we are privileged to have access to the National Security Archives in Washington D.C.We made two major observations out of this research : (1) Japanese diplomacy becomes multi-lateral in nature, as are shown in "Fukuda doctrine" and Ohira's Pacific Rim Concept. (2) As Japan takes more autonomous stance in foreign policy, it becomes on the other hand faced with "dual identity" that is a conflictual mentality of ones with the U.S.-Japan alliance and with Asia.It is discernible that Japan has enjoyed three historical opportunities to change its diplomacy more autonomous : in the 1950s, 1970s, and 1990s. Our observations and analysis imply that Japan's diplomacy in the 1990s is again destined to face similar challenges we already experienced in the 1970s.